Many devices and systems include a number of different types of sensors that perform various monitoring and/or control functions. Advances in micromachining and other microfabrication processes have enabled the manufacture of a wide variety of microelectromechanical system (MEMS) devices.
A particular type of sensor that includes a MEMS device is an accelerometer that uses a movable mass to detect acceleration or other stimulus along a sensing direction. In a typical accelerometer, the movable mass forms part of a plurality of differential capacitor pairs. The motion of the movable mass is detected by a sensing circuit coupled to the differential capacitor pairs, and the acceleration of the MEMS device can be calculated.
The movable mass in a typical MEMS device is suspended in proximity to a substrate with one or more suspension structures. The suspension structures greatly affect the overall sensitivity of the MEMS devices, and therefore greatly affect the overall performance of the device. The actual sensitivity of the MEMS device can be offset relative to the intended sensitivity due to modeling inaccuracies, product variation, or design changes. Additional problems with conventional MEMS devices include susceptibility to the effects of package deformation and stiction.
Accordingly, it is desirable to provide a MEMS device that is resistant to the effects of package deformation, reduces the occurrence of stiction, and has an easily adjustable sensitivity.